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Yadav S, Aloysius RP, Gupta G, Sahoo S. Granularity mediated multiple reentrances with negative magnetoresistance in disordered TiN thin films. Sci Rep 2023; 13:22701. [PMID: 38123674 PMCID: PMC10733403 DOI: 10.1038/s41598-023-50091-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 12/15/2023] [Indexed: 12/23/2023] Open
Abstract
Granular superconductors are the common examples of experimentally accessible model systems which can be used to explore various fascinating quantum phenomena that are fundamentally important and technologically relevant. One such phenomenon is the occurrence of reentrant resistive states in granular superconductors. Here, we report the observation of multiple reentrant resistive states for a disordered TiN thin film in its temperature and magnetic field dependent resistance measurements, R(T) and R(B), respectively. At each of the peak-temperatures corresponding to the zero-field R(T), a resistance peak appears in the R(B) around zero field which leads to a negative magnetoresistance (MR) region in its surrounding. These low-field negative MR regions appear for both perpendicular and parallel field directions with relatively higher amplitude and larger width for the parallel field. By adopting a granularity-based model, we show that the superconducting fluctuations in granular superconductors may lead to the observed reentrant states and the corresponding negative MR. Here, we propose that the reduction in the density of states in the fermionic channel due to the formation of Cooper pairs leads to the reentrant resistive state and the competition between the conduction processes in the single particle and Cooper channels result into the multiple resistive reentrances.
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Affiliation(s)
- Sachin Yadav
- CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - R P Aloysius
- CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Govind Gupta
- CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Sangeeta Sahoo
- CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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Arroyo-Gascón O, Baba Y, Cerdá JI, de Abril O, Martínez R, Domínguez-Adame F, Chico L. Persistence of symmetry-protected Dirac points at the surface of the topological crystalline insulator SnTe upon impurity doping. NANOSCALE 2022; 14:7151-7162. [PMID: 35380135 DOI: 10.1039/d1nr07120c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We investigate the effect of a non-magnetic donor impurity located at the surface of the SnTe topological crystalline insulator. In particular, the changes on the surface states due to a Sb impurity atom are analyzed by means of ab initio simulations of pristine and impurity-doped SnTe. Both semi-infinite and slab geometries are considered within the first-principles approach. Furthermore, minimal and Green's function continuum models are proposed with the same goal. We find that the Dirac cones are shifted down in energy upon doping; this shift strongly depends on the position of the impurity with respect to the surface. In addition, we observe that the width of the impurity band presents an even-odd behavior by varying the position of the impurity. This behavior is related to the position of the nodes of the wave function with respect to the surface, and hence it is a manifestation of confinement effects. We compare slab and semi-infinite geometries within the ab initio approach, demonstrating that the surface states remain gapless and their spin textures are unaltered in the doped semi-infinite system. In the slab geometry, a gap opens due to hybridization of the states localized at opposite surfaces. Finally, by means of a continuum model, we extrapolate our results to arbitrary positions of the impurity, clearly showing a non-monotonic behavior of the Dirac cone.
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Affiliation(s)
- Olga Arroyo-Gascón
- Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, C/Sor Juana Inés de la Cruz 3, E-28049 Madrid, Spain.
- GISC, Departamento de Física de Materiales, Universidad Complutense, E-28040 Madrid, Spain
| | - Yuriko Baba
- GISC, Departamento de Física de Materiales, Universidad Complutense, E-28040 Madrid, Spain
| | - Jorge I Cerdá
- Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, C/Sor Juana Inés de la Cruz 3, E-28049 Madrid, Spain.
| | - Oscar de Abril
- Departamento de Estructuras y Física de Edificación, Universidad Politécnica de Madrid, E-28040 Madrid, Spain
| | - Ruth Martínez
- GISC, Departamento de Física de Materiales, Universidad Complutense, E-28040 Madrid, Spain
| | | | - Leonor Chico
- Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, C/Sor Juana Inés de la Cruz 3, E-28049 Madrid, Spain.
- GISC, Departamento de Física de Materiales, Universidad Complutense, E-28040 Madrid, Spain
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